With the increase in cracking severity of FCC and the rise of hydroprocessing, the problem of processing byproduct n-pentane has become more significant. Some refineries isomerize the low 61.7 RON (research octane number) n-pentane to isopentane (RON=92.3). Isomerization of the n-pentane to isopentane leads, however, to an increase in gasoline volatility (RVP of n-pentane=15.6; RVP of isopentane=20.4); and environmental factors may limit the amount of isopentane usable in gasoline in the future.
Cyclopentene offers several advantages over n-pentane as a gasoline additive. Its research octane number is higher and its volatility is substantially lower, as shown below:
______________________________________ Compound RON MON BP (.degree.F.) ______________________________________ n-pentane 61.7 62.6 97 cyclopentene 93.3 69.7 112 ______________________________________
Cyclopentene can also be converted to cyclopentanol or cyclopentyl methyl ether for octane boosting. Cyclopentene is also an important monomer. V. Dragutan et al., Olefin Metathesis and Ring Opening Polymerization of Cycloolefins 160-163 (1985), incorporated herein by reference.
Therefore, it is an object of the present invention to provide a process for upgrading the poor octane n-pentane component of gasoline. It is a further object of the present invention to provide a product stream rich in cyclopentene.